EIF2AK2 and viral infectious disease: PKR was originally identified as an IFNβ inducible gene in response to viral infection, and plays an important role in type-I IFN production (Haller et al., 2006; Munir and Berg, 2013; Meurs et al., 1990; McAllister et al., 2012; Taghavi and Samuel, 2012).